Third Rock Ventures V, L.P.

CIK 1778071 · last filed 2026-04-21

Third Rock Ventures V, L.P. is a corporate insider who has filed 9 SEC Form 4 insider transactions across 2 companies since 2024. The most recent filing, for RAPP, was dated May 27, 2026. Across all open-market trades the lifetime net is +$4.8M, making them a net buyer over the disclosed history. Current disclosed insider exposure totals $676.4M across reported positions.

"Disclosed insider exposure" sums this person's most-recently-reported share counts across each company they're an insider in, multiplied by the current underlying price. It is not net worth — it misses retail holdings, private investments, real estate, index funds, and any company where the person isn't an SEC-reporting insider. For informational purposes only.

Disclosed Exposure

$676.40M

Companies

2

Total Filings

9

Lifetime Open-Market Net

$4.83M

Holdings By Company

Latest on-record share count from this person's most recent non-derivative Form 4 transaction in each company. Disclosed exposure = shares × current underlying price.

Symbol	Role	Shares	Price	Disclosed Exposure	Lifetime OM Net	Filings	Latest Filed
RAPP	10%+ Owner	7,678,446	$41.96	$322.19M	-$103.05M	1	2026-04-21
SEPN	10%+ Owner	10,427,250	$33.97	$354.21M	$107.88M	3	2025-02-26

Recent Filings

9 filings

Insider activity across all companies, newest first. Form 4 rows are post-trade confirmations (buys, sells, grants, exercises). Notice (144) rows are pre-trade notices of intent to sell restricted or control stock under Rule 144 — they may not all execute. Compare adjacent dates to see which notices became actual sales.

Filed	Symbol	Action	Net Shares	Net $	Link
2026-05-27	RAPP	Notice (144)	−18,572	-$742.9K	EDGAR
2026-05-11	RAPP	Notice (144)	−133,618	-$5.38M	EDGAR
2026-05-08	RAPP	Notice (144)	−5,018	-$202.3K	EDGAR
2026-05-07	RAPP	Notice (144)	−271,495	-$10.89M	EDGAR
2026-04-21	RAPP	Sell (S)	−2,556,030	-$103.05M	EDGAR
2026-04-17	RAPP	Notice (144)	−426,005	-$17.18M	EDGAR
2025-02-26	SEPN	Buy (P)	+113,166	$678.9K	EDGAR
2025-02-24	SEPN	Buy (P)	+6,242,052	$37.00M	EDGAR
2024-10-28	SEPN	Mixed	+49,882,374	$70.20M	EDGAR

Form 4 codes: P = open-market purchase · S = open-market sale · A = grant/award · M = option exercise · F = tax withholding at vest · G = bona-fide gift · D = disposition to issuer · J = other (see filing footnote). Only P / S codes carry directional signal.
Notice (144 / 144/A): Form 144 is a notice of intent to sell restricted/control stock under Rule 144, filed before the sale; 144/A is an amendment. Many notices are pre-scheduled under Rule 10b5-1 plans. A Form 4 with code S typically follows within a few days when the planned sale executes; missing follow-up Form 4s suggest the notice was cancelled or modified.